The mentorship and status of many Japanese women scientists by her establishment of the Saruhashi Prize and her many firsts

Katsuko Saruhashi (猿橋 勝子,Saruhashi Katsuko, March 22, 1920 – September 29, 2007) was a Japanesegeochemist who created tools that let her take some of the first measurements of carbon dioxide (CO2) levels in seawater. She later showed evidence in seawater and the atmosphere of the dangers of radioactivefallout and how far it can travel. Along with this focus on safety, she also researched peaceful uses of nuclear power.

Her other major area of significance involved raising the number and status of women scientists, especially in Japan. She established both the Society of Japanese Women Scientists and the Saruhashi Prize, which is given yearly to a female scientist who serves as a role model for younger women scientists.

Among her other honors, she was the first woman elected to the Science Council of Japan, to earn a doctorate in chemistry from the prestigious University of Tokyo, and to win the Miyake Prize for Geochemistry.

Saruhashi was born in Tokyo. She graduated from the Imperial Women's College of Science (predecessor of Toho University) in 1943. She then joined the Meteorological Research Institute, which belonged to the Central Meteorological Observatory (the later Japan Meteorological Agency), working in its Geochemical Laboratory and eventually becoming that laboratory's executive director in 1979.

In 1950, she started studying carbon dioxide (CO2) levels in seawater. At that time, CO2 levels were not recognized as important and Saruhashi even had to develop her own methods for measuring them.[1]:53

After the US conducted Bikini Atoll nuclear tests in 1954, the Japanese government asked the Geochemical Laboratory to analyze and monitor radioactivity in the seawater and in rainfall.[2] A Japanese fishing trawler had been downwind from the tests at the time they occurred, and its crew became ill from the effects. Saruhashi found that it took 18 months for the radioactivity to reach Japan in the seawater.[2]

By 1964, the radioactivity levels showed that the seawater in both the western and eastern parts of the North Pacific Ocean had mixed completely. By 1969, the traces of radioactivity had spread throughout the Pacific Ocean. This was some of the first research showing how the effects of fallout can spread across the entire world, and not only affect the immediate area.